1. Field of the Invention
The present invention relates generally to projection image display apparatuses and particularly to projection image display apparatuses having a function correcting a distortion of an image displayed on a projection surface.
2. Description of the Related Art
Projection image display apparatuses (hereinafter also referred to as projectors) may cause a so called image distortion. More specifically, between the optical axis of light projected by a projector and a screen or a similar projection surface, there may be a relative inclination, and accordingly, an image projected on the projection surface may distort at least in one of horizontal and vertical directions.
A projector having a correction function for correcting such image distortion is currently studied. More specifically, it is a projector that is switchable for example between performing a correction based on operating a key (i.e., manual correction), and detecting an angle of the projector, as disposed, and performing a correction based on the detected angle (i.e., automatic correction).
The above projector has a first trapezoid correction key operated to correct a projected image's trapezoidal distortion in a predetermined direction, and a second trapezoid correction key operated to correct the projected image's trapezoidal distortion in a direction opposite to that associated with the first trapezoid correction key. When the first or second trapezoid correction key is operated, a manual correction process is performed, whereas when the first and second trapezoid correction keys are operated, an automatic correction process is performed.
The above projector allows manual correction and automatic correction to be switched back and forth without the necessity of operating an otherwise separately provided, switching key. The projector can thus provide enhanced operability in switching manual correction and automatic correction back and forth.
Simply operating the first and second trapezoid correction keys to switch manual correction and automatic correction back and forth, however, may switch manual correction and automatic correction back and forth against the user's intention if the user operating a console panel inadvertently presses the first or second trapezoid correction key.
For example, if the automatic correction process is currently performed, and the first trapezoid correction key is inadvertently pressed, then the automatic correction process so far performed is stopped (or reset) and switched to manual correction, and the user must perform an operation once again from the beginning to correct distortion.